RCgothic

567s is more than the nominal duration for that burn. It's on about 4440s total compared to about 5400s expected, so still good for beyond-nominal life.

I suspect it would take a starship launch. Or at least, Dragon to rendezvous with a Starship. Starship has the capacity and space for airlocks, robotic arms and payload bay simultaneously, as well as plenty of margin to reach Hubble altitude and potentially re-boost it.

Better than planned for, but perhaps not as good as could be hoped for.

Estimate of MC-1 is about 16/17 m/s based on burn time, against 22m/s expected. Unclear as yet how this affects fuel reserves and life.

That would indeed be smart. Unfortunately the next flagship observatory, LUVOIR/HabEX is not currently being designed to take advantage of increased size and capacity. It'll be smaller than Webb and not due for completion until the 2040s.

I didn't know until today that the James Webb has a design life of 5 years, maybe up to a little over 10 depending on the accuracy of the L2 injection burn that just took place and the size of any required mid-course corrections. Unlike Hubble it needs to use fuel to maintain its position in L2 and this is a hard limit on life. The follow up to JWST, LUVOIR/HabEX is not due until the 2040s. This leaves the prospect that we could be left with a gap in major flagship space observatories. This article from earlier this year suggests that Hubble may well last until 2026 or later. https://www.technologyreview.com/2021/03/09/1020563/how-long-hubble-space-telescope-safe-mode-nasa/ Therefore, is there any prospect at all for another Hubble servicing mission, HST-SM5, to extend the life of the aging observatory? It appears the observatory has enough life left in it in order to prepare a servicing mission. And it's conceivable that this is a mission a crewed Starship with a robotic arm might be ideally suited to accomplish at a reasonable price. The payload wouldn't be big, so high LEO should be reachable in a single launch. How long might Hubble's life be further extended? Surely it would be worth it?

Again, it has no grapple fixture, and no ability to furl its sunshade to withstand any significant thrust.

The article is wrong in one respect - there is a crewed spaceship under design that could make it.out to L2 for a servicing mission. Starship could theoretically be made to have enough endurance and capability. However, it's true that Webb has no grapple fixture and no serviceable parts. There's no way to refuel it as far as I can tell.

I hadn't realised Webb's design life was just 5 years of science: Up to a little over 10 years if the L2 injection burn by the upper stage was perfect and little in the way of mid course corrections are required. One the fuel is gone, Webb will lose its ability to remain at L2 and keep the sunshade between itself and the sun. Unlike Hubble, which doesn't need to consume fuel to maintain its more-stable orbit in LEO.

The sort of launch abort system being talked about won't work on The Moon or Mars. There isn't enough atmosphere for the parachutes. Starship has to just work. Similarly, the landing burn is *far* scarier than the launch. There's no reasonable system that can mitigate that. Starship has to just work. Starship has to just work. Traditionally that's been difficult, but SpaceX is the only company who routinely gets their rocket stage and engines back for inspection post flight, so they know what sort of failures to look out for and how to mitigate them. Also, this whole discussion is very counting bridges before we come to them. Starship doesn't need to have crew on it for launch and landing. It doesn't need to launch or land with crew on earth at all until the safety has been demonstrated, likely through a combination of rapid launch cadence and analysis. NASA fully expects to crew-rate the system for launch from the moon, which has no survivable abort. There are plenty of moments in aviation where a failure probably wouldn't be survivable. Not every moment is practical to cover with an abort mode, and the mitigations aren't usually escape systems, but safety factors and redundancies. Let's all just relax about crew-rating for launch and landing from Earth for now. There's a lot of other hurdles to clear first

It wouldn't even be the first to be so.

There isn't a single great filter. Aside from being metaphorical, it's many-layered. It's every circumstance that would prevent life developing and every potential extinction event thereafter. Even civilisations that have survived to be communicable are still subject to it. The probability of extinction level events limit their lifespan and the window of time we have to notice them and make contact. Nothing has passed the great filter until it has put itself beyond any chance of extinction. Getting off planet removes many potential sources of extinction. It gets around anything that might happen to Earth. There's a step change in the risk of extinction and there will be much less chance of us getting filtered before our search for exosolar life can continue. Getting out of the solar system is another step change in our risk, as it removes us from vulnerability to anything that might happen to the sun. At each step it becomes much harder for war to take us out as well. Once we're out in the galaxy it's hard to think of anything that might take us all out at once, but even then a misplaced supernova or galactic collision might sterilise a portion of the galaxy. Or maybe among educated societies population collapse is just inevitable. We will never have passed the great filter entirely, but it is possible to take steps to minimise our vulnerability. One thing we can do is colonize Mars.

Lower tank now completely full.

One frosty boi: I think I recall the reason they don't fill completely to the top with LN2 is that it's denser than LCH4.

A single sample return mission as a prerequisite for a crewed mission is a joke. If the sample *does* find life, it's clearly so abundant that there's no particular need to take precautions because samples will be everywhere. Makes sense to send crew to study it. If it doesn't find evidence, that just means there wasn't any evidence in the one place it looked. Makes sense to send crew who can be more thorough in the search. And if we're sending crew either way, just send crew.

I've got little patience for planetary protection concerns standing in the way of crewed exploration. I want to see us advancing beyond Earth in my lifetime. Even if there is Martian life, it's not likely to be on the surface. The best way to find it is with human explorers. And once you have access to a proper lab, either in a local colony or by sample return, false positives are much less of a big deal. Delaying our expansion into the cosmos just in case we might disturb something that probably isn't there or is only there as a result of earthly diaspora risks human colonies never getting off world at all.

Oops.

I reckon a tanker with 9 engines in the upper stage could place substantially more than 255t into LEO (based on 150t with 6 Engines) with full reuse, not counting additional gravity losses for Superheavy's initial TWR being reduced from ~1.45 to ~1.27. A fully expendable version could do above 410t of pure payload to LEO, again not counting additional gravity losses during Superheavy's burn.

With stretched tanks the TWR may not be improved. Just been thinking - a few weeks ago, had a discussion about the world's most powerful rocket cores. Back then Starship was about 4th, behind only N1 Block A, Saturn SI-C, and SLS 5-segment SRB. With 9 engines Starship by itself is a definite 3rd. In terms of the world's most powerful rockets by thrust, 9-engine Starship by itself comes in at around 9th after Superheavy, N1, SLS, Saturn V, Energia, Long March 9 and Falcon Heavy.

So. So we think 6 vacuum engines on the upper stage is to make up a performance deficit, or is it just a: "We've got the space - why not? It's 42 engines total (lol) plus fewer tanker trips."

These go up to 11 now.

Cladding is now being added to the launch integration tower:

Apparently Russian state media is giving their space program a grilling:

How much does it weigh, this thruster? I'm betting more than 2.5N.